Traditionally rewind shells have been formed from wood. Wood, however, is prone to shrinkage if left to dry out, swelling if used in wet applications, and, is prone to warpage and sagging under loading, in which event the roll will become other than axially straight.
Further, it is necessary for the rewind shell to be provided at its ends with trunnions, whereby it can be supported in bearings of a rewind machine, and, appropriately rotated during a rewind operation by a drive provided by the rewind machine.
If a rewind operation must be halted while in progress, this can produce extremely high torsional stresses at the ends of the rewind shell, and thus produce extremely high shear stresses at the ends of the rewind shell and its interconnection with the associated trunnions. Unless extreme caution is exercised in the design of such rewind shells, and even in the event that extreme caution is exercised, the torsional forces can result in splitting of the wood rolls in the direction of the grain, thus severely impairing the structural integrity of the rewind shell and resulting in its possible disintegration and collapse under the weight of the supported textile material.